Oct 10 (Reuters) - The three major Wall Street indexes scaled new records on Tuesday, helped by gains in energy stocks and in Wal-Mart on the back of the company's $20 billion share buyback plan.

Wal-Mart rose 3.8 percent after the retail giant unveiled the buyback plan and forecast U.S. online sales would rise by about 40 percent in next fiscal year.

Oil prices gained more than 1 percent, supported by Saudi Arabian export cuts in November and comments from OPEC and trading companies that the market is rebalancing after years of oversupply.

All the 11 major S&P indexes were higher. The S&P energy index gained 0.85 percent, while Wal-Mart led the consumer staples index 1.16 percent higher.

At 9:38 a.m. ET (1338 GMT), the Dow Jones Industrial Average was up 50.31 points, or 0.22 percent, at 22,811.38, the S&P 500 was up 6.6 points, or 0.26 percent, at 2,551.33 and the Nasdaq Composite was up 22.53 points, or 0.34 percent, at 6,602.26.

The gains come after two rather tepid days that slowed the rally in stocks this year that was driven by strong corporate earnings, hopes of tax cuts and looser regulations.

But the rally has led to elevated valuations, which investors will look to justify through corporate profits in the upcoming third-quarter earnings season.

Earnings at S&P 500 companies are expected to have increased 4.8 percent last quarter, according to Thomson Reuters data, down from the double-digit growth recorded in the first two quarters of this year.

BlackRock and Delta Air Lines will kick off the earnings season on Wednesday, but the focus this week will be on big banks, with JPMorgan and Citigroup scheduled to report on Thursday.

"I think it will be a good earnings season," said Peter Cardillo, chief market economist at First Standard Financial. "It will be focused on individual stocks as opposed to earnings season as a whole."

Nvidia rose more than 3 percent after the chipmaker unveiled the first computer chips for developing fully autonomous vehicles.

Honeywell fell 1.25 percent after the manufacturer unveiled a corporate makeover that will tie its growth more strongly to aerospace technology and spin off other businesses as two publicly-traded companies.

Advancing issues outnumbered decliners on the NYSE by 2,018 to 495. On the Nasdaq, 1,725 issues rose and 632 fell. (Reporting by Sruthi Shankar in Bengaluru; Editing by Savio D'Souza)